Many companies have suspended spending on Twitter amid concerns over Musk’s content moderation plans for the site.
Musk said Twitter had seen a “huge” drop in revenue, blaming activists for putting pressure on advertisers.
In a tweet on Monday, the billionaire accused Apple of “censorship” and criticized its policies, including the fees it charges for purchases made in the App Store.
“Apple has mostly stopped advertising on Twitter. Do they hate free speech in America?” asks Musk.
Mack tweeted directly at the Apple CEO, asking, “What’s going on here @tim_cook?”
The social media platform owner also claimed that Apple had threatened to block Twitter from its app store, but did not say why.
Musk, who bought Twitter for $44 billion last month, is under pressure as some companies freeze their spending on the microblogging site.
He has said he hopes to make money by turning Twitter Verification into a paid subscription service, but currently most of the site’s revenue comes from advertising.
The Washington Post reported that Apple was the biggest advertiser on Twitter, spending $48 million on ads on the social network in the first quarter of 2022. Companies including Cheerios maker General Mills and Volkswagen are among the companies that have halted their Twitter spending in recent weeks.
Watchdog Media Matters reported last week that half of Twitter’s top advertisers have pulled their ads from Twitter amid concerns about where the microblogging site is headed.
According to US technology website The Verge, Apple’s media agency Omnicom advised the Silicon Valley giant to halt the ad out of concern for Apple’s “brand safety”.